Elastomeric-glass fiber products and process and elements for use in same



Nov. 26, 1968 A. MARZOCCHI 3,413,186

ELASTOMERIC-GLASS FIBER PRODUCTS AND PROCESS AND ELEMENTS FOR USE INSAME Filed Aug. 18, 1966 IN VENTOR 099w 7720mm United States PatentOffice 3,413,186 Patented Nov. 26, 1968 3,413,186 ELASTOMERIC-GLASSFIBER PRODUCTS AND PROCESS AND ELEMENTS FOR USE IN SAME AlfredMarzocchi, Cumberland, R.I., assignor to Owens-Corning FiberglasCorporation, a corporation of Delaware Continuation-impart ofapplication Ser. No. 218,724, Aug. 22, 1962. This application Aug. 18,1966, Ser. No. 573,267 The portion of the term of the patent subsequentto Nov. 22, 1983, has been disclaimed and dedicated to the Public 13Claims. (Cl. 161-176) ABSTRACT OF THE DISCLOSURE This invention isaddressed to the glass fiber reinforcement of products formed ofelastomeric materials wherein the glass fiber reinforcement isformulated of the glass fibers having an anchoring agent applied ontothe surfaces thereof after which the glass fibers are gathered togetherin the form of a bundle which is impregnated to apply a second coatingonto the glass fiber surfaces with an elastomeric composition andwherein the impregnated bundle of glass fibers is provided with anovercoating in the form of a second coat of elastomeric material. Thecomposite is then suitable for use in combination with the continuousphase elastomer in the fabrication of the glass fiber-elastomericproduct.

This is a continuation-in-part of my copending application Ser. No.218,724, now Patent No. 3,287,204, filed August 22, 1962, and entitled,Elastomeric-Glass Fiber Products and Process and Elements for Use inSame.

This invention relates to glass fiber-elastomeric products and tomethods and materials for use in the preparation of same and it relatesmore particularly to glass fiber-elastomeric products having improvedstrength, improved fiexibility, improved resiliency and wear, andimproved dimensional stability.

It is an object of this invention to produce and to provide a method forproducing glass fiberelastomeric products wherein a strong and permanentbonded relationship is established betwen the glass fibers and theelastomeric material forming the continuous phase of the glassfiberelastomeric product; whereby interfacial separation between theglass fiber system and the matrix of the continuous phase elastomericmaterial is substantially avoided thereby to maximize the utilization ofthe desirable properties of the glass fibers in the glassfiber-elastomeric product; in which the area between the glass fiberbundles is substantially completely filled with elastomeric materialwhich ties in with the continuous phase elastomer thereby to cushion theglass fibers for improvement in fiexural strength and wear and morecompletely to tie in the glass fiber component with the continuous phaseelastomeric system, and in which cure or vulcanization is carried intothe glas fiber system to form the elastomeric materials into asubstantially continuous phase or monolithic system which engulfs theglass fibers.

These and other objects and advantages of this invention willhereinafter appear and for purposes of illustration, but not oflimitation, embodiments of the invention are shown in the accompanyingdrawings, in which- FIG. 1 is a schematic elevational view of the glassfiber forming and sizing process; Y

FIG. 2 is a sectional view of a fragmentary portion of the glass fiberbundle produced by the sizing equipment of FIG. 1;

FIG. 3 is a schematic view of the arrangement of elements for theimpregnation of the glass fiber bundle;

FIG. 4 is a sectional view of a fragmentary portion of the impregnatedglass fiber bundle;

FIG. 5 is a schematic view of the arrangement of equipment forovercoating the impregnated glass fiber bundle;

FIG. 6 is a sectional view of a fragmentary portion of the overcoatedglass fiber bundle;

FIG. 7 is a sectional view of a fragmentary portion of a glass fiberbundle overcoated with a layer of elastomeric material; and

FIG. 8 is a sectional view of a fragmentary portion of the glassfiber-elastomeric product produced in accordance with the practice ofthis invention.

In the aforementioned copending application, description is made of aprocess and product wherein plural treatments are applied to the glassfiber system for the purpose of effecting a stronger and more permanentbonded relationship between the glass fibers and the continuous phaseeleastomeric material of the glass fiberelastomeric product. The pluraltreatments described in the aforementioned copending application includea first treatment in which the individual glass fibers are sized orcoated with a material containing an anchoring agent for intertying orinterbonding the elastomeric materials with the glass fiber surfaces; asecond treatment which is applied, preferably after the sized fibershave been gathered together into a glass fiber bundle such as a strand,yarn, cord or thread, and wherein the glass fiber bundle is impregnatedwith a composition containing an elastomeric material substantially tofill the interstices between the fibers and coat the glass fibers; andin which a third treatment is applied to the bundle of impregnated glassfibers wherein the impregnated bundle is overcoated with a compositionreferred to as an interfacial bonding coat which tends to assimilate thetreated glass fiber system with the continuous phase elastomericmaterial with which the treated glass fibers are combined in themanufacture of the glass fiber-elastomeric product and wherein theassimilation coat appears to operate in a manner to eliminateinterfacial separations between the continuous phase elastomer and thetreated glass fibers during the molding or vulcanizing operation.

In the aforementioned application, the assimilation coat is described asbeing formulated of an organo silicon compound formed of a silane havingfrom 1 to 3 hydrolyzable groups and an organic group attached to thesilicon atom containing an amine or an ethylenic group or in which theassimilation agent comprises an isocyanate, a phenolic end-blockedisocyanate, or ethylene dimethacrylate.

It has been found that considerable improvement can be experienced inthe glass fiber-elastomeric product produced when an outer sheath orlayer of an elastomeric material is employed instead of the assimilationcoat of the aforementioned copending application.

Various explanations are possible for the improvement that is secured bythe concepts of this invention. One logical explanation is indicated byobservation of the void that exists between the bundles of glass fiberswhen a number of such bundles are intertwisted or plied to form thecords used to reinforce the continuous phase elastomeric materials inthe manufacture of tires, belts and the like structures. Such voidsbetween the strands or bundles are incapable of being filled by theelastomeric material present as an impregnant in the glass fiber bundlesand the continuous phase elastomeric material is incapable of the amountof penetration of the cords formed of the glass fiber bundles with theresult that voids remain in the interior of the glass fiber system. Suchvoids permit movement of the glass fibers and permit destruction bymutual abrasion with resultant decreased life and utility of the glassfiber reinforcement. It also results in the utilization of only afraction of the fibrous components as a reinforcement for theelastomeric material and in the failure to achieve an effective tie-inbetween the fibers making up the interior of the cord and theelastomeric material.

Another possible explanation is the lack of cure through the glass fibersystem for complete integration with thecured or vulcanized continuousphase elastomer whereby a mono-lithic structure is incapable of beingformed as the final product.

When the impregnated glass fiber bundles are overcoated to provide asheath of elastomeric material, preferably a curable elastomericmaterial, a high concentration of elastomer is made available at thesurfaces of the glass fiber bundles and in the portion of the bundlesimmediately adjacent the voids running through the central portion ofthe cords or yarns whereby, during subsequent molding or cure,sufficient free rubber is available at the peripheries for flow into thevoids substantially completely to fill the voids and blend with thecontinuous phase elastomer for simultaneous cure of vulcanization. Thusthe glass fibers are cushioned one from the other and the void issubstantially completely filled with elastomeric material capable ofblending with the continuous phase elastomer and capable of curetherewith to overcome many of the deficiencies of the type previouslypointed out. The result is a composite structure of continuous phasecured elastomer with the bundle of glass fibers completely embedded andinter-tied into the cured elastomeric system without noticeableseparation or areas capable of separation in between.

Having described the theoretical concepts of this invention,illustration will now be made of the practice thereof with referencebeing made to the accompanying drawings. As in the aforementionedcopending application, the term elastomer is meant to include suchsynthetic elastomeric or rubber-like materials as neoprene, butadiene,chloroprene, isoprene, butyl rubber and the like, or copolymers thereofwith acrylonitrile, styrene and the like, and especially elastomericmaterials which are curable or vulcanizable by reaction to a set stageby peroxide or through sulphur linkages. The term is also meant toinclude natural rubbers and modifications thereof such as chlorinatedrubber and the like.

The term glass fibers is meant to refer to continuous glass fibers inthe form of filaments, strands, yarns, bundles, cords and fabrics formedthereof and it is intended also to include discontinuous glass fibers inthe form of glass wool fibers and yarns and fabrics formed thereof orfibers of the continuous or discontinuous types which have been cut,chopped or otherwise reduced to shorter lengths, but usually to lengthsgreater than about inch.

The practice of this invention will correspond to the practice in theaforementioned copending application up to and through the firsttreatment of the glass fibers to apply a size coating containing ananchoring agent onto the glass fiber surfaces and the impregnation ofthe bundle of glass fibers with a composition containing an elastomericmaterial as hereinafter described.

Example 1.Preparation of treated glass fibers In FIG. 1 of the drawings,a schematic illustration is made of a means for the production ofendless lengths of glass fibers including a glass fiber melting furnacehaving a bushing 12 on the bottom side thereof provided with a pluralityof openings. The streams 14 of molten glass, flowing gravitationallyfrom the openings in the bushing, are rapidly attenuated into finefilaments 16 by winding the filaments, after they have been gatheredtogether to form a strand 18, about a rapidly rotating winding drum 20.

' The separate filaments of glass fibers are coated before andpreferably as they are being gathered together into a single bundle orstrand. For this purpose, use is made of an applicator 22, which may bein the form of a wiping pad wet with the fluid treating composition andover which the glass fiber filaments are drawn as they are gatheredtogether to form the strand 18.

The composition applied to the glass fibers in forming is formulated tocontain an anchoring agent, preferably gamma-aminopropyltriethoxysilane, or other anchoring agent as will hereinafter be described. Thecoating composition may be applied from a solution in a suitablevolatilizable carrier, as illustrated by the following compositions Aand B, but it is preferred to embody the anchoring agent as a componentin a conventional size composition of the type represented by theformulations C and D. When employed in a treating composition, as incompositions A or B, or in combination with a film forming material andlubricant, as in the size compositions C and D, it is desirable to makeuse of a composition containing the anchoring agent in an amount withinthe range of 0.1 to 5.0 percent by weight and preferably in an amountwithin the range of 0.5 to 2.0 percent by weight. The followingcompositions are given by way of illustration, but not by way oflimitation, of the treating compositions which may be employed as thefirst coating applied to the glass fiber surfaces:

Composition A.0.1-5.0 percent by weight gammaaminopropyltriethoxysilane. Remainder water.

Composition B.0.5-2.0 percent by weight gammaaminopropyltriethoxysilane; 0.3-0.6 percent by weight glycerine. Remainder water.

Composition C Percent by weight Partially dextrinized starch 8.0Hydrogenated vegetable oil 1.8 Cationic wetting agent (lauryl amineacetate) 0.4 Non-ionic emulsifying agent 0.2 Gamma-aminopropyltriethoxysilane 1.0

Remainder water.

Composition D Percent by Weight 3 2 In the foregoing examples, thegamma-aminopropyltriethoxy silane can be replaced, in whole or in part,with an equivalent amount of another amino silane, such asgamma-aminopropylvinyldiethoxy silane,gamma(triethoxysilylpropylamide)propyl amine, N(gamma-triethoxysilylpropyl propylamine, gamma (triethoxysilylpropyloxy)propylamine,beta-aminoallyltriethoxy silane, para-aminophenyltriethoxy silane,aniline silane derivatives, and other amino silane compounds or organosilicon compounds, such as the corresponding silanol or polysiloxaneformed of a silane having at least one but not more than three highlyhydrolyzable groups such as a halogen group, a short chain alkoxy groupor amino group and having an organic group attached directly or throughan oxygen atom to the silicon atom in which the organic group containsless than 8 carbon atoms and also contains a free amine or anunsaturated group or a carboxyl group. Instead of making use of thedescribed organo silicon compound, use can be made of Werner complexcompounds in which the carboxylato group coordinated with the trivalentnuclear chromium atom contains less than 8 carbon atoms and a groupidentified as an amine, an ethylenic group or a carboxyl group.

It is preferred to make use of a composition in which the anchoringagent is embodied as a component of a glass fiber forming size, such asin compositions C or D, thereby to provide the glass fibers with acoating which enhances the processing as well as the performancecharacteristics to enable the glass fibers to be formed into yarns,cords and fabrics, while also permitting the treated glass fibers to beused as a reinforcement with the elastomeric material without thenecessity previously to remove the protective size composition forreplacement with an anchoring agent.

Instead of wiping the treating composition onto the glass fibers, thetreating composition can be applied by other conventional coatingsystems, such as by spray coating, roller coating, flow coating and thelike. It is preferred to apply the treating composition directly ontothe bare glass fibers, as described in the forming operation, or afterthe original size has been removed.

Treatment of the glass fibers in forming, in the preferred practice ofthis invention, results in a treated glass fiber which has a lowignition loss and in which the filaments of glass fibers are capable ofeasy separation in the glass fiber bundle to enable fuller penetrationof the strand of glass fibers in the subsequent treatment to impregnatethe strand and coat the fibers with the impregnating compositioncontaining an elastomeric material.

Glass fibers, coated in accordance with Example 1, can be dried atelevated temperature, but it is the usual practice to allow the sized orcoated glass fibers to air dry thereby to provide the bundle 18 of glassfibers 16 in which the glass fibers are individually coated with a sizecoating 23.

Example 2.Impregnation of glass fiber bundle Composition E Parts byweight Neoprene rubber 100 Powdered magnesium oxide 4 Zinc oxide 5Carbon black 15 Thiate B (trialkyl thiourea accelerator) 1 Toluene 700Composition F Parts by weight Natural rubber latex-resorcinolformaldehyde resin dis- Composition G Parts by weight Resorcinolformaldehyde resin 2 Formalin, 37% solution 1.4 Concentrated ammoniumhydroxide solution 5.0 Vinylpyridine butadiene-styrene terpolymer latex(50% solids) 25 Neoprene rubber latex (50% solids) 50 Butadiene latex(60% solids) (Pyolite 2104) 7.4 Sodium hydroxide solution 0.2

Water 58.0

Impregnation of the formed strand 18 of glass fibers can be made by wayof a solvent bushing or it can be achieved by other conventional meansfor impregnation, such as by immersion of the bundle of glass fibers ina bath of impregnating composition. Referring more specifically to FIG.3 of the drawings, the treated strands 18 of glass fibers are unwoundfrom the spool 24 and advanced continuously over rollers 26 and 28 intothe bath 30 of the treating Composition E, F or G housed in a container32. From the container, the impregnated strand of glass fibers is passedupwardly through a wiping die 34 whereby excess composition is removedfrom the impregnated glass fiber strand and whereby the impregnatingcomposition is worked into the strand more substantially to fill theinterior thereof. The impregnated glass fiber strand or bundle 38 isadvanced through a drying oven 36, maintained at an elevated temperaturesuch as at a temperature within the range of 250450 F. to remove thediluent and partially to advance the elastomeric components to a stageless than a fully cured or vulcanized stage.

From the drying oven, the impregnated strand 38 of glass fibers is drawnthrough the processing steps by means of power actuated pullers 44 andrewound on drum 46.

It is desirable to achieve as complete impregnation of the strand orbundle as is possible. Under such circumstances, the tremendous amountof surface area available between the individual glass fiber filamentsand the impregnating elastomeric composition will contribute frictionalresistance to relative movements in a manner to militate againstslippage between the elastomeric material and the glass fibers. Thisadditional resistance will operate to improve the bonding relationshipestablished between the elastomeric component and the glass fibersurfaces. Thus the fibers will be in a position markedly to influencethe physical and mechanical properties of the elastomeric system and tocontribute exceptionally good reinforcement to the elastomeric product,especially in the combination which includes an elastomeric overcoating,as hereinafter defined, to integrate the impregnated glass fiber bundlewith the continuous phase elastomer.

Impregnation or coating with the elastomeric impregnating compositioncan be improved by the technique of flexing or bending the strand orbundle of glass fibers while in the bath of the impregnatingcomposition, as by running the strand or bundle over bars or otherflexing or bending devices. Instead, or in combination therewith, fullerimpregnation can be achieved by the use of pressure dies or by thepassage of the glass fiber bundle through the device to provide forpulsations between high and low pressures to work the composition intothe bundles while withdrawing occluded gases, or fuller impregnation canbe achieved by the more recent techniques of ultrasonic vibration duringimpregnation.

In the product that is formed in Example 2, the fibers 16 making up theglass fiber bundle 18 will be cushioned one from the other by theimpregnating elastomeric composition 40.

In the aforementioned copending application, description is made of thetreatment of the impregnated strand or bundle to provide an overcoatingof gamma-aminopropyltriethoxy silane or other amino silane orisocyanate, phenolic end-blocked isocyanate, or ethylene dimethacrylate,referred to as an assimilation coat, which operates substantially toeliminate the interface between the coatings on the glass fibers and theelastomer forming the continuous phase of the glass fiber-elastomericproduct.

It has been found that instead of the assimilation coat, or in additionthereto, best results are secured when the impregnated glass fiberstrand 38 is overcoated with an elastomer, preferably an elastomericmaterial which is the same as or compatible with the elastomericmaterial forming the continuous phase and the elastomeric material withwhich the glass fiber strand or bundle is impregnated and in which theelastomeric overcoating is preferably also formulated with a curing orvulcanizing agent for advancement of the elastomer to the cured orvulcanized stage along with the cure or vulcanization of the continuousphase elastomer during the exposure to heat and pressure for molding theelastomeric product.

In the preferred practice, the overcoat of elastomeric material isapplied from a fluid rubber cement composition, as represented by thefollowing example:

7 Biphenylamine-acetone reaction product (Aminox) 1 Diphenylguanidine(DPG) .2 N-cyclohexyl-Z-benzothiazolesulfenamide (Santocure) 1 Sulphur1.75

Example 4 Parts by weight Carboxylated butadiene-styrene rubber 80Natural rubber 20 Zinc oxide 3 Stearic acid 5 Carbon black 50 Pine tar 5Biphenylamine-acetone reaction product (Arninox) 1 Diphenylguanidine(DPG) .2 N-cyclohexyl-Z-benzothiazolesulfenamide (Santocure) 1 Sulphur1.75

The compositions are stirred into toluene or other rubber solvent in anamount to form a solution containing about by weight solids.

The impregnated strand or bundle 38 of glass fibers is immersed in thefluid cement composition, as by advance ment of the impregnated strand38 downwardly into a bath 50 of the cement composition and then upwardlyabout rollers 52 through a die 54 for metering a proper amount of thecement onto the impregnated glass fiber bundle. The overcoated strand orbundle is advanced through an elevated temperature zone 56 or oven forthe removal of diluent and then to a rewinding position 58. It isdesirable to effect sufficient drying to enable the strand or bundle,with the overcoating 60, to be plied and/ or twisted into reinforcingcords 62.

It will be apparent from the schematic illustration of the cord 62 thatis formed, that the overcoated strands Will appear in the interior ofthe cord to provide the additional amount of rubber needed substantiallycompletely to fill any voids formed in the cord of twisted orintertwisted strands of the glass fiber bundles. Such flow of theadditional rubber in the overcoating will occur to fill the voids inresponse to the compression during the application of heat and pressureduring the molding operation. The rubber in the overcoating will blendwith the rubber 64 of the continuous phase and cure therewith to producean integrated structure.

It will be understood that other elastomeric materials can be employedto form the overcoating 60 and that other solvents can be used informulating the fluid composition for overcoating the impregnatedstrands of glass fibers.

As previously pointed out, it is preferred to make use of an elastomericcomponent which is compatible both with the rubber of the impregnant andthe rubber of the continuous phase 64. It will be understood also thatthe cement can be applied by other coating systems, such as by diecoating, flow coating and the like to provide a relatively heavy coat 60on the impregnated bundle 38 of glass fibers 16.

Another technique for overcoating the impregnated strand or bundle ofglass fibers comprises the encasement of the strand 38 in a sheath, suchas a spaghetti 66 formed of the elastomeric material. This can beaccomplished most effectively and efliciently by extrusion of theelastomeric material about the impregnated bundle of glass fibers as acore whereby the impregnated bundle of glass fibers 38 becomes sheathedwithin a tube 66 of elastomeric material. The described overcoated andimpregnated strands of glass fibers can be plied, twisted, andintertwisted with other such strands or bundles to form the reinforcingcord 62 for combination with the continuous phase elastomer. Any of theelastomeric materials previously described can be extruded to form thecontinuous overcoating 66 about the impregnated strand of glass fibers,such as butadiene-styrene rubber hydrochloride, isoprene, chloroprene,butyl rubber and the like.

The extruded rubber is insufiiciently cured thereby to enable cold flowor flow under heat and pressure to fill the voids and to cure with thecontinuous phase elastomer to tie in all of the fibers with theelastomeric component.

The treated glass fibers can be embodied in any arrangement desired inthe combination with a matrix of elastomeric materials for themanufacture of glass fiberelastomeric products.

The concepts embodying this phase will be described with reference tothe use of the plural coated glass fiber system in the manufacture of abelting formed of elastomeric material. It will be understood, however,that other combinations with the elastomeric coated fibers and matrix ofelastomeric material can be secured in the fabrication of otherelastomeric-glass fiber products to be characterized by high strength,good flexure, good dimensional stability, relative inertness, hightemperature resistance, lack of fatigue and the like.

Example 5.Fabrication of an eldless driving belt In the manufacture ofbelting by the process of this invention, a belt forming mandrel isfirst wrapped with a layer of neoprene rubber, hereinafter referred toas a cushion coat. Over the cushion coat another layer of a lesserloaded neoprene rubber is wrapped to provide what is hereinafterreferred to as an adhesion coat. Then the cords or strands of rubbercoated glass fibers are wrapped around the adhesion coat, with orwithout previous coating of the surface of the adhesion coat with atacky rubber cement to hold down the cords and to minimize shifting ofthe cords from a predetermined wrapped position thereby to permit moreprecise placement of the fibers in the final assembly. Over the layer ofrubber coated glass fiber strands, yarns or cords, another cushion coatof neoprene is wrapped to form the completed assembly.

The multiple layers of materials wrapped about the tube forming mandrelare then sliced circumferentiallyin substantially parallel relationshipwith the glass fibers to form laterally separated strips. The strips areremoved by collapsing the mold.

First the strips are skived or cut to V shape in the fabrication of a Vbelt. Thereafter the strip is flipped by wrapping the V cut strip with arubber impregnated fabric. The V shaped belt can be formed directlywithout the skiving step and/ or without the flipping step, as bymolding directly under heat and pressure in a mold of V shape incross-section.

Vulcanization of the assembly is carried out in the mold at atemperature of about 350 F. under positive pressure.

The cords formed of the plural coated glass fiber system described canalso be used effectively as the reinforcing element in the manufactureof rubber tires by arrangement of the cords in the conventional mannerin a bias wound or in a radially wound system in the tire carcass. Suchplural coated fiber system can be fabricated into ply fabrics by anyconventional method and employed in the tire assembly as anyconventional ply.

The green tire is subjected to a normal molding process of heat andpressure for vulcanization of the elastomeric material in a tire mold.During the vulcanization process, the rubber in the overcoat 66 flowsoutwardly from the cords while the rubber stock 64 making up the matrixflows inwardly into the area between the cords. Thus the rubber in theovercoat and the rubber stock of the tire become intermingled forvulcanization together so that the vulcanization process penetrates intothe interior of the reinforcing glass fiber cords.

I claim:

1. A glass fiber reinforcement for elastomeric-glass fiber productscomprising a bundle formed of a plurality of glass fibers, a firstcoating on the individual glass fiber surfaces containing an anchoringagent for intergrating the elastomeric material with the glass fibersurfaces, an elastomeric composition in the form of a second coatingimpregnating the bundle of glass fibers coated with the anchoring agentsubstantially to coat the glass fibers in the bundle, and a thirdcoating containing an elastomer about the impregnated bundle of glassfibers, said elastomer in the third coating being compatible with theelastomeric component impregnating the bundle of glass fibers and theelastomeric material in the elastomeric-glass fiber product, wherebysaid reinforcement will readily bond with the elastomeric material inthe elastomeric-glass fiber product when placed therein.

2. A glass fiber reinforcement as claimed in claim 1 in which theanchoring agent is an organo silicon compound comprising a silane havingfrom 1 to 3 highly hydrolyzable groups and an organic group attached tothe silicon atom containing a group selected from the group consistingof an amine, an unsaturated ethylenic group and a carboxyl group.

3. A glass fiber reinforcement as claimed in claim 1 in which theanchoring agent is gamma-aminopropyltriethoxy silane.

4. In the method of producing glass fiber-elastomeric products havingimproved mechanical and physical properties, the steps of forming glassfiber reinforcements for said products by treating glass fibers to coatthe glass fibers with a first coating containing an anchoring agent forintegrating an elastomeric material with the glass fiber surfaces,gathering a plurality of the coated glass fibers into a glass fiberbundle, impregnating the glass fiber bundle with a compositioncontaining an elastomeric material to form a second coat on the coatedglass fibers, and coating the impregnated glass fiber bundle with athird coating containing an elastomeric material which is compatiblewith the elastomeric material in the impregnating composition and withthe elastomer of the product, whereby said reinforcements will readilybond with the elastomeric material in the elastomeric-glass fiberproduct when placed therein.

5. The method as claimed in claim 4 in which the anchoring agent is anorgano silicon compound formed of a silane having from 1 to 3 highlyhydrolyzable groups and an organic group attached to the silicon atomcontaining a group selected from the group consisting of an amine, anunsaturated ethylenic group and a carboxyl group.

6. The method as claimed in claim 4 in which the anchoring agent isgamma-aminopropyltriethoxy silane.

7. The method as claimed in claim 4 which includes the step of heatingthe impregnated glass fiber bundle prior to the application of the thirdcoat to advance the cure of the elastomeric material in the impregnatingcomposition to less than the fully cured state.

8. The method as claimed in claim 4 in which the third coating ofelastomeric material applied to the impregnated bundle of glass fibersis formed by the process of extruding the elastomeric material about theimpregnated bundle of glass fibers.

9. The method as claimed in claim 4 which includes the steps ofprocessing the impregnated and coated glass fiber bundles by plying toform reinforcing cords of the glass fiber bundles.

10. The method as claimed in claim 4 which includes the steps ofcombining the glass fiber reinforcements with the elastomeric materialforming the matrix of the product and molding the system under heat andpressure to advance the elastomeric materials to the cured stage.

11. The method as claimed in claim 4 which includes the steps ofprocessing the impregnated and coated glass fiber bundles by twisting toform reinforcing cords of the glass fiber bundles.

12. The method as claimed in claim 4 which includes the steps ofprocessing the impregnated glass fiber bundles by twisting andintertwisting to form reinforcing cords of glass fiber bundles.

13. A glass fiber reinforcement as claimed in claim 1 in which the thirdcoating about the bundle of impregnated glass fibers comprises a tube ofelastomeric material sheathed about the bundle of glass fibers.

References Cited UNITED STATES PATENTS 2,827,099 3/1958 Youngs 156-3293,252,278 5/1966 Marzocchi et al. 156-308 ROBERT F. BURNETT, PrimaryExaminer.

R. A. FLORES, Assistant Examiner.

